Control circuitry for matrix printer



Aug. V12, 1969 K. G. RuMsEY ETAL 3,461,236

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o m .v n N mbz-cm E. wwatbo u om o u m v n N 5258 @2E u States Patent O U.S. Cl. 178-30 S Claims ABSTRACT F THE DISCLOSURE Control circuitry for a matrix printer comprises twostate circuits controlling operation of respective printing members and each is switchable between ltwo conditions to determine the beginning and end, respectively, of the printout of each character portion by the associated member; a diode matrix whose output leads are' connected to respective two-state circuits; a ring counter connected to pulse the matrix input leads consecutively; and switching circuitry to bias a combination of pairs of matrix diodes for each different character, each such pair being associated with an output lead and one of the pair operating, on receiving a pulse from the associated input lead, to switch the two-state circuit associated with its output lead to one condition, signifying commencement of a print-out of a particular character portion, and the other element of the pair operating, when subsequently pulsed, to switch the two-state circuit to its second condition signifying the end of the print-out of the character portion, thereby providing a proportional print-out.

This invention relates to control circuits for operating a printing or like device and more especially but not solely to a device of the kind which relates to a printing display device in which the characters are formed by a set of hammers which are operated in combinations and in sequences to print out the shape of the various characters required to be printed.

The invention consists in a control circuit arrangement comprising switch means, means operative from the switch means to select a sequence of pulse combinations for operating a character forming printing device and for initiating relative movement of the printing device and the medium on which printing is to be effected, means to transmit the selected pulse combinations in sequence to the printing device and means to reset the means operative from the switch means and the transmit means and to arrest the relative movement of the printing device and printing medium.

The control circuit arrangement conveniently also includes means for transmitting a space signal and for transmitting line feed and to reverse the relative movement between the printing means and printing medium at the end of a line.

The invention will be further described -with reference to the accompanying circuit diagram of an annunciator transmitter according to the invention.

The annunciator transmitter is designed to feed one or more annunicator printers. A typewriter or similar keyboard is provided, the other working parts of the transmitter being entirely electronic. When the key corresponding to the letter, figure or symbol required is depressed, the appropriate switch is actuated causing a number of diodes in a diode matrix to be selected. Only one switch, marked switch A and only that part of the diode matrix corresponding to the letter E are shown in the drawing.

3,461,236 Patented Aug. 12, 1969 ICC Actuating switch A causes a signal to be sent to timing circuit B and, by operating an on/ot circuit C, to the brake and clutch circuits in the receiving printers, causing the printer carriages to move. After 40 milliseconds, the reset circuit D is turned oit by B, causing the two-state on/oif circuits E1 to E7 to be released and the l6-ring counter F to commence counting. F has its input connected to a SO-cycle-per-second source, such as the electrical mains, so that it is caused to operate at the rate of 50 counts per second. The 16 outputs from F are connected through the diode matrix and amplifiers 1 to 7 to lil-E7. The diodes selected from the diode matrix by switch A are so arranged as to put El-E7 into the on or oil condition to a predetermined pattern. The twostate circuits E are connected to the circuits actuating the 7 printing hammers in each printing receiver, so that each two-state circuit controls a given printing hammer. When a two-state circuit is in the on condition, the appropriate printing hammer is caused, by the circuits in the printing receivers, to print at the rate of 50 operations per second and when in the off condition, the appropriate hammer is prevented from operating.

It will be seen that the spaces between letters are generated by B causing the printer carriages to move 40 milliseconds before printing takes place.

As counter F can count up to 16, there are a possible maximum of 16 blows per printing hammer. Which of these 16 are used is governed by the diodes selected in the matrix. In the example used, i.e., the letter E, no part of the matrix is used after position l1 on counter F.

In any horizontal line in the matrix, the first diode selected always turns the appropriate two-state circuit E on and the last diode selected always turns it olf. When all seven two-state circuits have been turned o, this condition is detected by the 7 input gate G. This gate then supplies a signal that turns reset D on and this in turn resets counter F to zero and holds circuits E1-E7 in the olf condition. Gate G also supplies a signal which turns on/off circuit C off and this causes the carriages in the printers to stop. As can be seen from the drawing, in the case of the letter E, this operation of gate G will occur after the counter has reached its eleventh position. This system, therefore, ensures that automatic allowance is made for the varying widths of diiierent letters and that the spaces between the letters of a word are constant. The cycle of selecting a character, deciding when the hammers in the printers shall or not print, detecting the end of the character, and resetting the counter and two-state circuits to their initial state, is then complete. When another key is depressed, the cycle is repeated.

A separate key is used to provide a space signal. When this is depressed, the timing circuit H is energised and on/otf circuit C is turned on. After 200 milliseconds, H turns C off again. As C operates the carriage drive circuits in the printer, this results in the carriages moving for the 200 milliseconds during which C is in the on condition. This movement of the carriages with no hammers in operation causes a space to be formed.

A further key is provided which, when depressed, closes a switch causing a signal to be transmitted to the printers, actuating the combined line feed and carriage return mechanisms. Interlocking is provided to ensure that no key can be depressed while a letter or other signal is being transmitted.

There are, therefore, a total of 9 channels connecting the transmitter to the printers, one for each of the 7 printing hammers, one for the carriage drive mechanism and one for the combined carriage return and line feed mechanism. This could, however, be combined into any number of channels less than 9 and, in the extreme case, into one channel only, by the use of tone or modulation techniques.

We claim:

1. Control circuitry for a character-forming device having a line of printing members extending transversely of the line of characters to be printed and each operated for a predetermined duration during print-out each character to print a predetermined portion of the latent character image as it passes beneath the member, the circuitry including: two-state circuits controlling operation of respective printing members and each switchable between two conditions to determine the beginning and end, respectively, of the print-out 0f each character portion by the associated member; a matrix composed of rows of output leads crossing lines of input leads and connected to respective two-state circuits; a pulse generating counter connected to pulse the input leads consecutively; an array of elements disposed at respective crossing positions of the input and output leads and each switchable between two states to transmit a pulse received from the associated input lead through the output lead to switch one of the two-- state circuits between its two conditions; and switching circuitry operated for each character to be printed to bias a unique combination of pairs of elements for each different character, each such pair being associated with an output lead and one of the pair operating, on receiving put lead through the output lead to switch one of the twostate circuit associated with its output lead to one condition, signifying commencement of a print-out of a particular character portion, and the other element of the pair operation, when subsequently pulsed, to switch the two-state circuit to its second condition signifying the end of the print-out of the character portion.

2. Circuitry as claimed in claim 1, in which the control elements comprise diodes having their cathodes connected to the output leads some of which are connected to a source of negative voltage by the switching circuitry for each selected character.

3. Circuitry as claimed in claim 1, including a gate responsive to all of the two-state circuits returning to their initial conditions thereby detecting completion of print-out of a selected character, said gate thereupon transmitting a signal, and a reset circuit responsive to said signal to return the counter to its starting position and to apply a holding signal to the two-state circuits to hold them in the same condition.

4. Circuitry as claimed in claim 3, in which the switching circuitry on selection of a particular character transmits a lirst signal and a second signal, and including a timing circuit which is responsive to said rst signal to deenergize the reset circuit after a pre-set time interval, and an on/of circuit responsive to said second signal to control operation of a printer carriage brake and a carriage driving clutch.

5. Circuitry as claimed in claim 1, in which the members comprise hammers connected to deliver hammer strokes at the same repetition rate as the pulse delivered by the counter during the period in which the two-state circuits are in said one condition.

References Cited UNITED STATES PATENTS 2,932,692 4/1960 Hunt 178-30 2,977,415 3/1961 Van Breeman 178-30 3,085,132 4/1963 Innes 178-30 3,174,427 3/1965 Taylor 178-30 3,286,029 11/1966 Simshauser et al. 17830 3,324,240 6/1967 Kleinschmidt et al. 178-30 3,359,366 12/1967 Magleby 178-30 THOMAS A. ROBINSON, Primary Examiner U.S. Cl. XR. 178-17 

